Various types of electronic applications can include transmitters, or the like, which can include voltage-controlled oscillators (VCOs) and power amplifiers. In such circuits, a VCO can be in the generation and/or modulation of a signal for transmission (e.g., as part of a clock circuit, such as a phase-locked loop), and the power amplifier can be used to apply gain to the signal prior to transmission (e.g., and/or for setting output impedance, etc.). Both the VCO and the power amplifier typically include one or more inductors, for example, as part of respective inductive-capacitive (LC) oscillator networks. Relatively high currents passing through the inductor(s) of the power amplifier can tend to magnetically couple back to the inductor(s) of the VCO, which can tend to pull (e.g., detune) the frequency of the VCO.
Conventionally, multiple categories of approaches are used to mitigate this pulling. One category seeks to ensure that the frequency of the VCO is as close to identical as practical to the frequency of the power amplifier. Conceptually, when the frequencies are the same, any magnetic coupling from the power amplifier should tend not to pull on the frequency of the VCO (e.g., the magnetic coupling may, instead, reinforce oscillation of the VCO at the shared frequency). A second category seeks to maintain a large separation between the frequency of the VCO and the frequency of the power amplifier (e.g., so that the power amplifier frequency is well outside the operating frequency band of the VCO). For example, an additional modulator circuit can be used, so that the signal output by the VCO is modulated to a very different frequency prior to being received by the power amplifier. Conceptually, sufficiently separating the frequencies should effectively avoid any magnetic coupling.